Tyson Gay, who won a silver medal in the men's 400-meter relay at the 2012 London Olympics, accepted a one-year suspension Friday for using a product containing a banned substance. Gay also accepted loss of results dating to July 2012.

Colorado Springs, Colo. — Sprinter Tyson Gay accepted a one-year suspension Friday after testing positive for a banned substance nearly a year ago and returned the silver medal he won in the men's 400-meter relay at the 2012 London Olympics.

The US Anti-Doping Agency announced that Gay's one-year ban began June 23, the day his sample was collected at the US championships. His sanction is subject to appeal by International Association of Athletic Federations (IAAF) and by the World Anti-Doping Agency, USADA said Friday.

As part of the penalty, Gay, the American record-holder in the 100, also accepted loss of results dating to July 15, 2012, the date of when he first used a product that contained a banned substance. He was a member of the relay team at the London Games that finished second to a Jamaican team anchored by Usain Bolt. The Americans set a national record with a time of 37.04 seconds. Gay has given his medal back to the United States Olympic Committee.

USADA said in a statement that upon receiving notification of his positive tests, Gay voluntarily withdrew from all competition prior to the 2013 world championships in Moscow and has not competed since.

The 31-year-old Gay could've been given a penalty twice as long, but received consideration after assisting USADA in the investigation into his positive test. USADA said he tested positive for the presence of an exogenous androgenic anabolic steroid.

"We appreciate Tyson doing the right thing by immediately withdrawing from competition once he was notified, accepting responsibility for his decisions, and fully and truthfully cooperating with us in our ongoing investigation into the circumstances surrounding his case," USADA CEO Travis Tygart said in a statement.

Gay was at the top of his game at the 2007 world championships in Osaka, Japan, capturing gold in the 100, 200 and 400 relay. That was just before the emergence of Bolt, who's dominated the sprint scene ever since.

Meanwhile, Gay has dealt with one injury after another, including strained groins, hamstring tightness and hip surgery. He set the American 100 record in 2009 when he finished in 9.69 seconds. Bolt has the world record at 9.58.

Before last season, Gay's test results never raised any red flags. He even took part in USADA's "My Victory" program — in which athletes volunteer for enhanced testing to prove they're clean.

He tested positive out of competition last May. A month later, Gay recorded a positive at the U.S. championships, where he won the 100 and 200 meters, and was notified. He surrendered his spot at worlds.

Gay said at the time: "I don't have a sabotage story. I don't have any lies. I don't have anything to say to make this seem like it was a mistake or it was on USADA's hands, someone playing games."

In a statement released by USA Track and Field, CEO Max Siegel said the organization is "gravely disappointed any time an athlete uses performance-enhancing drugs, and Tyson Gay's case serves as a lesson about the consequences of making poor decisions. We appreciate that Tyson accepted responsibility and has assisted USADA by providing information to help battle the use of PEDs."

There are no major international meets in track this summer, but U.S. championships will be held June 26-29 in Sacramento, California. And while Gay could become eligible for that meet, the disqualification of his results dating to 2012 has taken away his qualifying time for the meet. He could petition the track and field committee for consideration, but USATF has said it hasn't received such a petition yet.

Gay has until June 16 to enter a petition in order to gain entry into the meet.